The coffee giant said Monday it is adding four new, slightly sweetened varieties of its successful Via instant brew. The flavored instant coffee is the latest in a series of new products from Starbucks as it tries to find new ways to grow after years of overexpansion of its cafes.

The flavors -- mocha, vanilla, caramel and cinnamon -- will be sold in Starbucks stores this fall, though no date has been announced. The single-serve packets will be added to grocery store shelves early next year and will be backed by a promotional campaign backed by free samples along with television, print and online advertisements.

Launched nationwide last September, Via racked up more than $100 million in worldwide sales in the 10 months since its debut.

The packets, which dissolve in water, were initially sold in two roasts -- a medium-bodied Colombia and bold Italian Roast. Since then, the company added a decaf variety and a medium-roast designed for instant iced coffee and now sells Via in four countries.

Then in June, Starbucks began selling a new line of ground coffee in grocery stores called Starbucks Natural Fusions -- the company's first-ever flavored ground coffee. That coffee, brewed traditionally and without sweeteners like the new Via products, was the company's first entry into the $265 million premium flavored coffee market.

The company's internal research shows that 60 percent of buyers of its packaged coffee drink some sort of flavored coffee from competitors, which means there's significant opportunity to snatch dollars from rivals.

"These are people that are drinking Starbucks coffee today," Young-Scrivner said. "But I think the flavor will bring in new customers as well."

Starbucks won't release prices or packaging sizes for the flavored Via. But officials said its price tag would be similar to iced Via, which sells $5.95 for five single-serving packages.